Ancient mitochondrial DNA and population dynamics in postclassic Central Mexico: Tlatelolco (ad 1325–1520) and Cholula (ad 900–1350)

Abstract

The past composition and genetic diversity of populations from Central Mexico during the Postclassic period (ad 900–1520) are still little understood. Two of the largest centres of ancient groups, Tlatelolco and Cholula, declined after European conquest and questions about their relationships with other Central Mexican cities and ritual activities have been debated. Tlatelolco was a Mexica group that practiced the Quetzalcoatl cult and human sacrifice, including the sacrifice of children, while Cholula was considered the main pilgrimage centre and multiethnic city during the Postclassic. This study analysed the mitochondrial DNA control region of 28 human skeletal samples to estimate the genetic affinities of individuals buried at Tlatelolco and Cholula. Amelogenin analysis and whole genome sequencing (WGS) were also applied to determine the sex of the 15 Tlatelolco subadults from sacrificial contexts. Networks, PCoA and Nei genetic distances were calculated to compare Tlatelolco and Cholula haplotypes with available ancient haplotype data from Mesoamerican groups and the two borderland areas, Paquime and Greater Nicoya. Mitochondrial haplogroups were characterized for 11 of the 15 samples from Tlatelolco (73%) and 12 samples out of 13 from Cholula (92%), revealing the presence of four distinct Amerindian mitochondrial lineages at Tlateloloco, A (n = 6; 55%), B (n = 2; 18%), C (n = 1; 9%) and D (n = 2; 10%); and three lineages in Cholula, A (n = 5; 42%), B (n = 5; 42%) and C (n = 2; 16%). Statistical analysis of the haplotypes, haplogroup frequencies and Nei genetic distances showed close affinity of Tlatelolco’s subadults with ancient Mexica (Aztecs) and closer affinities between Cholula and the Xaltocan of the Basin of Mexico. Sex determination of Tlatelolco subadult sacrifice victims revealed that 83% were females, in contrast to previous studies of subadult sacrificial patterns at the site. Together, these results demonstrate the multi-ethnic nature of religious and economic centres in Postclassic Central Mexico.